Trione-Annadel State Park, a 5,092-acre park at the north edge of Sonoma Valley in Santa Rosa, is shaped by volcanic geology, varied habitats, and a long human history. Southern Pomo and Southern Wappo people quarried obsidian here for tools for at least 3,000 years. After Spanish colonization, ranching and farming spread, and the land passed through Rancho Los Guilicos, William Hood, and later local families before entering the state park system in 1971. Cobblestone and perlite were also mined here. The park is notable for northern oak woodland, wetlands, recreation trails, and for protection efforts that led to its renaming in 2016, despite development pressure, budget threats, and recent wildfires.